First Drive: Volkswagen XL1 Plug-in Diesel Hybrid

A dozen years ago, Volkswagen embarked upon a project to design a vehicle that can travel 100 kilometers using merely one liter of diesel fuel. VW logically dubbed the car the L1. The company this week allowed a small group of American journalists to drive the fourth iteration of the car—this one known as the XL1—on a 40-minute trip near the company’s headquarters in Wolfsburg, Germany. I was part of the group that experienced the XL1’s iconoclastic blend of four efficiency strategies:

Plug-in hybrid power

Sleek aerodynamics

Severe light-weighting

Efficient (very) small diesel engine design

Combining these strategies has a multiplicative impact—allowing the XL1 to beat its 100-km goal by 10 percent, providing 110 kilometers on a single liter of fuel. (That equates to about 260 miles per gallon.) What's even more impressive is the XL1's design—a fun, stylish piece of automotive innovation that updates car coolness for the 21st century, swapping out horsepower and brawn as the measure of appeal and attraction, with an irresistible high-tech quirky charisma.

Gutsy, Eco, Chic

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(Photo: Brad Berman)

The XL1 seats only a driver and a passenger to the side, staggered a few inches toward the rear of the car. The body design is wide in front, and tapers to much thinner proportions toward the back. While providing as much as 30 miles of all-electric capability from a 5.5-kilowatt-hour battery, stomping on the accelerator wakes up a 0.8 liter rear-mounted 48-horsepower engine—just enough internal combustion propulsion, combined with electricity, to move the car along with brisk city traffic or not feel left behind on Germany's famed highways. When that small diesel engine comes online, it loudly clatters, nearly directly into the passenger cabin. In an effort to save weight, sound dampening was ignored—making every flutter of the engine, as well as every bump in the road or scraping screech from the car’s ceramic brakes—a visceral experience.

This intrusion into the cabin is part of the car's gestalt, along with its scissor doors, side-view cameras (to replace mirrors), and futuristic shape. Power steering was also eschewed in the name of light weighting, making turns at any decent speed an athletic feat not dissimilar to steering a Tesla Roadster. It all adds up to a ton of fun. Efficiency is not a matter of sacrifice or anemia. VW made the XL1 gutsy and chic.

Even the tiny slot of a passenger window, manually wound up and down, felt analog-hipster. Of course, the small opening will make it impossible to ever receive a Supersized fast food meal at a drive-through window. Just as well—there’s absolutely zero chance this car will make its way to the United States.

Read My Lips: De-mon-stra-tion

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Volkswagen's Dr. Ulrich Hackenberg. (Photo: Brad Berman)

Volkswagen will use a manufacturing process that looks and smells a lot like mass production at its factory in Osnabruck, Germany—but merely 250 XL1 units will be made. Approximately the first 50 will be put on loan to VIPs for a few weeks at a time, or to Germany-based customers who submit proposals to demonstrate how the XL1 can be incorporated into a daily sustainable lifestyle. The first of those loaners have already been given out. Next, a “real” production run of 200 cars—that's right, just 200 cars—will be sold or leased like any other VW automobile. No pricing info is yet available.

In a meeting with the journalists, Dr. Ulrich Hackenberg, a chief product specialist on the Volkswagen board, yesterday repeated the word “demonstration” when speaking about the XL1. He also said that the company needed to invest in a full range of automotive technologies and fuels (from compressed natural gas and fuel cells to plug-in hybrids and, of course, diesels) to achieve corporate global efficiency targets. More importantly, Hackenberg said the use of a very small diesel engine, like the XL1’s two-cylinder 830cc TDI Clean Diesel, combined with a parallel plug-in hybrid layout, could soon be applied to another VW model—perhaps a subcompact like the Up city car it sells in Europe.

It’s too early to tell if a prospective future model will be made in greater quantities, or reach American shores. But for me, at this stage, it’s enough to know that the slick head-turning ultra-lightweight XL1 exists—and can serve as a compelling vision for quantum leaps in aerodynamics and high-tech appeal. The Cd of the XL1 is a super-slippery 0.19. It weighs only 1,753 pounds, by virtue of its carbon-fiber body.

The car’s plug-in hybrid system consists of a 48-horsepower two-cylinder diesel engine, a 27-horsepower electric motor, a seven-speed DSG dual-clutch automatic transmission, and a lithium-ion battery. This design is now in VW’s back pocket, ready to be used if regulations demand, or brought forward in some partial form or fashion to a future VW electro-diesel model. And it's ready to be emulated by any car company with a brave vision.

Smooth Sailing

Speed is not the XL1’s raison d’etre. It has a top speed of 99 miles per hour, but accelerates from 0 to 62 mph in a leisurely 12.7 seconds. After hitting highway speeds, take your foot entirely off the accelerator—and there’s absolutely no regenerative braking. That’s what VW product people call sailing.

With the slightest depression of the brake pedal, the regen braking comes back into action—feeding braking energy into the liquid-cooled lithium ion battery pack. If you find the sweet spot on the accelerator pedal—just barely into the throttle—the driver can simultaneously maintain highway speed, while producing some level of regen—essentially converting diesel fuel into battery power on the fly from this parallel hybrid system. The press release for the car reads: “This super-efficient Volkswagen can cruise at a constant 62 mph while using just 8.3 horsepower.”

To save weight and improve aerodynamics, VW engineers removed side-view mirrors. Instead, they used low-profile cameras and a monitor inserted into the door.

I only had a half-hour in the car, so there wasn’t enough time to fully play with how to wring the greatest efficiency and driving pleasure out of the system. But what I did experience was a blast, albeit mildly compromised by the car’s lack of good visibility. I’m 6’ 4”—so street signs above the road were hard to see, no matter how I tilted the driver’s seat. The side view monitors—while in all likelihood very faithful to what you would see in an analog side mirror—were hard to trust. I kept trying to peer over my shoulder, but the camera provides the only unobstructed view for checking if it's safe to move into adjacent lanes.

Leading the Way

After my relatively brief drive of the XL1, I returned to VW’s Autostadt car theme park and history museum. There, on display, were two previous versions of the XL1, one from 2002 and another from 2009. While those previous L1 prototypes are cool—in a Batmobile way—this latest XL1 I drove felt much more like a real and practical form of city mobility, complete with side-by-side passenger comfort and enough cargo space for two pieces of carry-on luggage.

Okay, so it won’t be coming to the U.S. and won’t be produced beyond 250 models. VW is not hiding that fact—as opposed to some of its competitors that pass off their limited-run plug-in models as “production” vehicles, but make merely enough to exactly comply with regulations.

All of the technologies found in the XL1 are ready-for-primetime, even if it isn’t exactly economical to throw all of them together in one car, as VW has done. Nonetheless, the XL1 can be shown off as an impressive vision of what’s possible when great aerodynamics, lightweight design, and plug-in diesel technology are integrated.

At the same time, I can't forget what VW’s chief of electric technology Dr. Rudolf Krebs told me earlier this year. “We want to become the leader in electrification,” he said. Then he flashed a slide that showed seven plug-in hybrids and two pure EVs in VW’s product roadmap in the next two years. If any smidgen of quirky geeky excitement from the XL1 finds its way to those cars, Volkswagen could shake up the world of electrified vehicles with a fresh alternative to ultra-efficient travel.

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Comments

Let's say this car - or one similar to it - could someday be made available with Protean hub motors, which appears to be a promising product that we'll actually see over the next year or so, and solid electrolyte lithium sulfur batteries (no liquid thermal management needed, 4X the energy density of today's lithium ion cells,) such as those that have been recently announced by Oak Ridge National Laboratories. Oh yeah . . . build the cells into the floor.

Then, you wouldn't need the inboard electric motor, diesel engine and trans-axle. You'd have a lot of luggage space under that hatchback and a way to integrate in a rear window.

Even in it's present real world form, though, this has got to be one of the sweetest rides around. I wish all cars were like this.

It seems a shame all this engineering work went into a 98% finished product and now they are not even attempting to sell more than a few samples. And this car took far more engineering work than say my Roadster, as a for instance......

I keep hearing that VW is a leader in electric car technology. Except that when I go to the local dealership, I can't find anything that would lead me to believe that.

It wasn't all that long ago. Mike I, that I thought automotive scale hub motors were largely the stuff of science fiction. But it looks as if they're really advancing now. Protean is putting them into production in early 2014. Their first one - designed for 18" diameter truck wheels - will be followed by a passenger car sized one in 2015. The promise is for something that contains controllers, can operate at significant time periods while completely submerged in water and cost only a few thousand dollars per unit. Quite a few OEMs - including Tesla - are following Protean's developments closely and some are investing.

On a car as light as the XL1, you would only need a pair of them. With little else inboard and taking care with battery placement, it's now conceivable to envision a car like this to have unencumbered front AND rear cargo areas of consequence.

And you're preaching to the choir here, Bill, when it comes to Volkswagan's glacially slow EV rollout and concurrent bragging. I wish they'd just get on with it. At least, though, they're actually going to sell a couple hundred of these . . . which is a couple hundred more copies than any number of EV show cars they've passed under our noses this past decade. Some progress is better than no progress, I suppose.

The XL1 is a halo car, obviously. It is possible they can "drop" this drivetrain into the Up! or maybe the Up! Lite concept they showed a while back - that would be cool. I agree that an EV version of this car would be a good thing, though it would be better as a front wheel drive, I think.

It is also interesting that it is a parallel hybrid, with only the plug, regen and the "sweet spot" method of charging. Is there are way to "force" it to switch modes; like if you want to save some charge for the end of the trip?

I'm not sure people here know how VW work.
This is essentially a production test bed for a group of technologies which will likely find their way into production models, but probably not in the same combination.

The diesel motor, for instance, may well be adapted for use in volume models, as may the various ideas on lightweighting embodied here.

This is simply the way their development cycle works.

They prefer to test ideas in a small volume production environment, to see in more detail how they work out.

Limited production test bed vehicles are all well and good. I fully understand how that concept works. I think the frustration Bill and I have, Davemart, is that Volkswagen spends a lot of time bragging about how they're a leader in electric cars and - drum roll please - they haven't really made any . . . at least in any realistic quantities and available for general sale in all the markets they serve. It's this sort bravado, which has been going on for years, that's so
galling . . .

Benjamin, I agree with your idea of the Protean motors. Though the actual efficiency of that design is still to be tested (higher suspension weight and tuning). Though a magneride system should solve many of the harshness issues of that layout. I guess the automotive industry will change dramatically in the coming years, if these new testbeds are any indication. Also the success of Tesla. Hope to see a more vibrant and disperse automotive industry, than the largely monolithic ones today.

WHY can't VW put this technology into a regular GOLF or JETTA? Why does it have to be some ugly space age Jetsons car? Combine DIESEL + HYBRID and put it on the market now. What is so hard about it??? This should have been on the market 10 years ago!